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We examine the long-term evolution of the intra-hour variable quasar, J1819+3845, whose variations have been attributed to interstellar scintillation by extremely local turbulent plasma, located only 1–3 pc from Earth. The variations in this source ceased some time in the period between June 2006 and February 2007. The evolution of the source spectrum and the long-term lightcurve, and the persistent compactness of the source VLBI structure indicate that the cessation of rapid variability was associated with the passage of the scattering material out of the line of sight to the quasar. We present an extensive analysis on the linear polarization variations and their relation to total intensity variations. The proper motion of polarized features in the quasar jet is found to be sub-luminal. Systematic time delays between Stokes I, Q and U, in combination with the structure of the source obtained from 8.4 GHz VLBI data confirm the estimate of the screen distance: 1–2 pc, making the screen one of the nearest objects to the Solar system.

We report on the X-ray and multiwavelength properties of 11 radio-quiet quasars with weak or no emission lines identified by the Sloan Digital Sky Survey (SDSS) with redshift z = 0.4-2.5. Our sample was selected from the ...

We present a pilot search for variable and transient sources at 1.4 GHz with the Australian Square Kilometre Array Pathfinder (ASKAP). The search was performed in a 30 deg2 area centred on the NGC 7232 galaxy group over ...

Spectral features absorbed against some radio quasars exhibit ~50 mJy variations, with the lines varying both relative to the continuum and, when several lines are present, even relative to one another. We point out that ...

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Curtin University would like to pay our respect to the indigenous members of our community by acknowledging the traditional owners of the land on which the Bentley Campus is located, the Wadjuk people of the Nyungar Nation; and on our Kalgoorlie Campus, the Wongutha people of the North-Eastern Goldfields.Watch our traditional Aboriginal welcome